The BGS Lexicon of Named Rock Units — Result Details

Fernieslack Palaeosol Bed

Sandy, clayey, silty sand diamicton, brown. Interpreted as a truncated gleyed brown earth soil profile developed under temperate climate conditions. The truncated palaeosol bed represents the pedogenically modified upper c.0.80m of the Rottenhill Till Formation. Pedogenic development is indicated by the following properties: the upper 0.70m of the deposit has a strong brown colour in contrast to the lower part of the deposit which is yellowish brown. It also displays coarse mottles of yellowish red and greyish brown to brown due to Fe oxide segregation. Mafic igneous and granite clasts have been converted to gruss in situ and clay minerals show alteration from illite to mica-smectite up profile. Disrupted void argillans (evidence of clay translocation and subsequent disruption) and erect pebbles have been recorded in thin section, indicating that the palaeosol has superimposed cold climate soil features.

Definition of Lower Boundary:

The lower boundary of the palaeosol bed is gradational (over c.0.10m) between the pedogenically modified diamicton and the relatively unaltered diamicton of the Rottenhill Till Formation.

Definition of Upper Boundary:

The upper boundary is a subhorizontal, planar, erosion surface overlain by gravelly sandy diamicton of the Corsend Gelifluctate Bed. The upper horizon of the palaeosol bed (not preserved) was eroded at some point prior to deposition of the gelifluctate.

Thickness:

To 0.80m

Geographical Limits:

Buchan, northeast Scotland. The palaeosol bed is only known within the immediate vicinity of Kirkhill Quarry (infilled) (centred on NK 0120 5285) and Leys Quarry (disused) (centred on NK 0040 5250) on Sheet 87W (Ellon).

North face of Kirkhill Quarry (infilled), 7km southeast of Stricken, Buchan, northeast Scotland. Note: The Fernieslack Palaeosol Bed was moderately well developed in all faces of Kirkhill Quarry (infilled), but studied most intensively in the north face. Connell, Hall and Romans. 1984.

Reference Section

Northeast face of Leys Quarry (disused), 6.5km southeast of Stricken, Buchan, northeast Scotland. Note: This reference section is included to demonstrate a site where Rottenhill Till Formation diamicton displays evidence of in situ weathering (in situ mafic and felsic igneous clasts have been converted to gruss), but there is no clear evidence of palaeosol horizon development. Hall and Jarvis. 1993.

Connell, E R and Hall, A M. 1987. The periglacial history of Buchan, Scotland. 277-285 in Boardman, J (Editor), Periglacial Processes and Landforms in Britain and Ireland. Periglacial processes in Britain and Ireland. Cambridge University Press, Cambridge.